A continuous-motion automatic packaging machine rapidly applies secondary packaging to multiple individually packaged products such as canned or bottled consumables for greater ease of transportation, storage, sale, and consumer utilization. A typical packaging machine integrates several modular stations, including a carton erector, case packer, carton sealing station, palletiser, and interconnecting conveyor systems that convey the products through the various modular stations and into each of a series of cartons. It is known to provide a packaging machine with a modular or integral carton feeder that erects cartons, such as sleeve type cartons provided as carton blanks that are partially assembled and collapsed into tubular sleeves prior to being fed into the packaging machine. A typical carton feeder includes three rotary vacuum wheels, each including vacuum cups for engaging and disengaging cartons that are selectively activated and deactivated by means of valves controlled by a computer processor.
When the packaging machine is running, it is critical to supply the carton feeder with a steady stream of carton blanks, which may be folded beforehand and secured into a pre-erected configuration, such as flattened tubular sleeves or flattened basket-style carriers. An operator loads the carton blanks into a hopper, which then conveys the carton blanks to the feeder on advancing belts that are continuously or intermittently driven. In order for the feeder wheel to efficiently engage each carton, the cartons must be consistently stacked. Thus, such packaging machines are sensitive to the manner in which the operator fills the hopper—requiring loading to be extremely orderly and consistent. Gaps between carton blanks cause the blanks to tilt, resulting in more frequent misses by the feeder wheel. Conversely, overcompensating for gaps by overdriving the advancing belts of the hopper causes the carton blanks to press against one another excessively, again increasing the occurrence of misses by the feeder wheel as well as increasing the likelihood that carton blanks will be expelled prematurely.
Attempts to compensate for this sensitivity include creating a pressure break that reduces the pressure translated from the line of carton blanks in the hopper to the feeder wheel. The pressure break is created by interposing a magazine between the feeder wheel and the hopper. The transition between the hopper and the magazine is stepped down significantly such that the cartons blanks in the magazine are several inches lower than the carton blanks in the hopper. Because the hopper is separate from the magazine, the magazine needs separately driven roller belts to convey carton blanks toward the feeder wheel. Although such configurations may reduce the pressure in the magazine, there is still no guarantee that the advancing belt will not run excessively to exceed the ability of the pressure break to adequately relieve the pressure. Furthermore, the inclusion of separate roller belts significantly limits the ability of such magazines to support the weight of the carton blanks.
There is a need, therefore, for a packaging machine having an infeed station that is less sensitive to filling anomalies, and that reduces the likelihood of misfeeds.